EQ1: How does the carbon cycle operate to maintain planetary health?

Question 1

Where is most of the world’s carbon locked away?

Answer 1

In terrestrial stores as part of a long term geological cycle.

Question 2

What does the biogeochemical carbon cycle consist of ?

Answer 2

Carbon stores of different sizes (terrestrial, oceans and atmosphere).

Question 3

What is the carbon cycle?

Answer 3

The cycle by which carbon moves from one Earth sphere (atmosphere, hydrosphere, lithosphere and biosphere) to another. It is a closed system made up of interlinked subsystems which are open and have inputs and outputs.

Question 4

List the 4 Earth spheres.

Answer 4

• atmosphere
• hydrosphere
• lithosphere
• biosphere

Question 5

What are carbon stores? (also known as sinks/reservoirs)

Answer 5

Function as sources (adding carbon to the atmosphere) and sinks (removing carbon from the atmosphere).

Question 6

What are carbon fluxes? (also known as flows or processes)

Answer 6

Movements of carbon from one store to another; provide the motion in the carbon cycle.

Question 7

A balanced carbon cycle is important in sustaining other Earth systems, but what is the balance being increasingly upset by?

Answer 7

Human activities.

Question 8

Where is carbon?

Answer 8

Everywhere. In rocks and soils, in all forms of life and in the atmosphere.

Question 9

What does the wellbeing and functioning of the Earth depend on?

Answer 9

Carbon and how it cycles through the Earth’s systems.

Question 10

Carbon exists in different forms, depending on the store, what forms are these?

Answer 10

• 𝗮𝘁𝗺𝗼𝘀𝗽𝗵𝗲𝗿𝗲: as carbon dioxide (CO₂) and carbon compounds such as methane (CH₄)
• 𝗵𝘆𝗱𝗿𝗼𝘀𝗽𝗵𝗲𝗿𝗲: as dissolved CO₂
• 𝗹𝗶𝘁𝗵𝗼𝘀𝗽𝗵𝗲𝗿𝗲: as carbonates in limestone, chalk and fossil fuels, as pure carbon in graphites and diamonds
• 𝗯𝗶𝗼𝘀𝗽𝗵𝗲𝗿𝗲: as carbon atoms in living and dead organisms

Question 11

What does each sphere consist of?

Answer 11

• atmosphere = gases (the air)
• hydrosphere = all water e.g oceans and lakes
• lithosphere = solid earth
• biosphere = all life

Question 12

Examples of carbon fluxes.

Answer 12

• erupting volcanoes
• burning fossil fuels
• photosynthesis
• decomposition
• respiration
• weathering and erosion
• rock cycle

Question 13

Examples of carbon stores.

Answer 13

• atmosphere
• ocean surface
• food web
• phytoplankton
• shellfish and corals
• sedimentary rocks
• plants
• coal, oil and gas

Question 14

What do stores vary in?

Answer 14

Size, capacity and location

Question 15

What is the important distinction in the biosphere?

Answer 15

Between terrestrial and oceanic locations.

Question 16

What are carbon fluxes between the carbon stores of the carbon cycle measured in?

Answer 16

Either pentagrams or gigatonnes of carbon per year.

Question 17

Where is the carbon on earth stored? (3 places)

Answer 17

• terrestrial (lithosphere, biosphere)
• atmospheric
• oceanic

Question 18

What are the major fluxes between?

Answer 18

Between the oceans and the atmosphere, and between the land and the atmosphere via the biological processes of photosynthesis and respiration.

Question 19

What do fluxes vary in?

Answer 19

In terms of their rates of flow, but also on different timescales.

Question 20

Define systems.

Answer 20

How the carbon cycle operates with inputs, stores and flows and outputs.

Question 21

Define equilibrium.

Answer 21

How the carbon cycle is maintained in a balance.

Question 22

Where is organic carbon found?

Answer 22

In plant material and living things.

Question 23

What do plants take carbon through?

Answer 23

Photosynthesis and respiration, which is completed in seconds. They then released it by respiration.

Question 24

What is the rate of decomposition?

Answer 24

Completed at varying rates.

Question 25

Where is inorganic carbon found?

Answer 25

In rocks as bicarbonates and carbonate (the Earth’s largest carbon store)

Question 26

What controls the speed of photosynthesis and respiration?

Answer 26

Sunlight, moisture and temperature. If it’s too dark, hot or cold, they decrease. Low levels of CO₂ in the atmosphere also reduce the speed of the cycle.

Question 27

What are the three forms of carbon?

Answer 27

• inorganic
• organic
• gaseous

Question 28

What is inorganic carbon released by?

Answer 28

Chemical weathering, over decades or hundred of years.

Question 29

How fast are the rate of fluxes between the Earth’s surface, plants, and atmosphere?

Answer 29

Fast - a matter of months or seasons.

Question 30

Why do carbon flux rates vary globally?

Answer 30

Since regional climates influence rates of photosynthesis and respiration, CO₂ fluxes vary with latitude.

Question 31

Where are CO₂ levels higher?

Answer 31

In the Northern Hemisphere, because it contains greater landmasses and greater temperature variations than in the Southern Hemisphere.

Question 32

Describe the process of photosynthesis in plants.

Answer 32

Plants take carbon dioxide and water from the atmosphere to promote plant growth and produce nutrients.

Question 33

What does respiration do?

Answer 33

Releases CO₂ into the atmosphere.

Question 34

What happens during the transformation of carbon into sedimentary rock?

Answer 34

Movement of carbon from oceans (skeletons, fossils) to mantle.

Question 35

What is carbon sequestration?

Answer 35

The process by which carbon dioxide is removed from the atmosphere and held in solid or liquid form. It’s the process that facilitates the capture and storage of carbon.

Question 36

What is outgassing?

Answer 36

The release of gas previously dissolved, trapped, frozen or absorbed in some material e.g rock.

Question 37

What are carbon pumps?

Answer 37

The processes operating in the oceans that circulate and store carbon.

Question 38

What is chemical weathering?

Answer 38

The decomposition of rock materials in their original position by agents such as water, oxygen, CO₂ and organic acids.

Question 39

𝗖𝗔𝗦𝗘 𝗦𝗧𝗨𝗗𝗬: What’s an example of out-gassing?

Answer 39

In 2010, the Eyjafjallajökull volcano in Iceland erupted - emitting CO₂ into the atmosphere, plus extensive ash clouds that spread across Europe.

Question 40

𝗖𝗔𝗦𝗘 𝗦𝗧𝗨𝗗𝗬: As a result of the eruption of the 2010 Eyjafjallajökull volcano in Iceland, how much CO₂ was emitted?

Answer 40

Between 150,000 and 300,000 tonnes of CO₂ per day - placing it in the same emissions league as small-to-medium sized European countries such as Portugal or Ireland.

Question 41

𝗖𝗔𝗦𝗘 𝗦𝗧𝗨𝗗𝗬: Despite emitting up to 300,000 tonnes of CO₂ per day, how much did the volcanic eruption in Iceland contribute to global emissions of greenhouse gases?

Answer 41

It contributed less than 0.3% of global emissions of greenhouse gases in 2010.

Question 42

How do volcanic eruptions essentially rebalance the cycle?

Answer 42

• The impact of emissions from volcanic eruptions is to send extra CO₂ into the atmosphere, which leads to rising temperatures, increased evaporation and higher levels of atmospheric moisture.

• This, in turn, leads to increased acid rain, which weathers rocks and creates bicarbonates that will eventually be deposited as carbon on the ocean floor. The process is slow- perhaps a few hundred thousand years- but this chemical weathering process slowly re-balances the carbon cycle.

Question 43

How may ash counteract climate change?

Answer 43

Could block some solar radiation. However, CO₂ does essentially increase climate change.

Question 44

What does geological carbon result from?

Answer 44

The formation of sedimentary carbonate rocks - limestone and chalk - in the oceans.

Question 45

Where is biologically derived carbon stored?

Answer 45

In shale, coal and other sedimentary rocks.

Question 46

What is most of the carbon in the world?

Answer 46

Locked in terrestrial stores e.g Earth’s crust (100,000,000 Pg) as part of the long-term geological cycle, rocks. Comes from carbonate rocks. It’s mainly limestone, formed in the oceans

Question 47

Where is most lithospheric carbon is concentrated?

Answer 47

In the sedimentary rocks of the crust.

Question 48

How many Pg of carbon is there in the lithosphere?

Answer 48

Over 100 million Pg

Question 49

Give an example of one of the Earth’s largest carbon store.

Answer 49

The Himalayas. This is because the mountains started life as ocean sediments rich in calcium carbonate derived from crustaceans, corals and plankton. Since these sediments have been upfolded, the carbon they contained has been weathered, eroded and transported back to the oceans.

Question 50

How did carbon derived from plants and animals in shale, coal and other rocks form?

Answer 50

Made up to 300 million years ago from the remains of organisms. These remains sank to the bottom of rivers, lakes and seas and were subsequently covered by silt and mud. As a consequence, the remains continued to decay anaerobically and were compressed by further accumulations of dead organisms and sediment.

The subsequent burning of these fossil fuels has released the large amounts of carbon they contained back into the atmosphere.

Question 51

What is the geological carbon cycle?

Answer 51

A natural cycle that moves carbon between land, oceans and atmosphere.

Question 52

What are the six important stores and fluxes within the geological carbon cycle?

Answer 52

➊ Terrestrial carbon, held within the mantle, is released into the atmosphere as CO₂ when volcanoes erupt - outgassing.
➋ CO₂ within the atmosphere combines with rainfall to produce a weak acid (carbonic acid or acid rain) that dissolves carbon rich rocks, releasing bicarbonates = chemical weathering.
➌ Rivers transport weathered carbon and calcium sediments to the oceans, where they are deposited.
➍ Carbon in organic matter from plants, animals, shells and skeletons sink to the ocean bed when they die, building up strata of coal, chalk and limestone.
➎ Carbon rich rocks are subducted along plate-boundaries and eventually emerge again when volcanoes erupt.
➏ The presence of intense heating along the subduction plate boundaries changes sedimentary rock into metamorphic rock. CO₂ is released by the metamorphism of rocks rich in carbonates during this process.

Question 53

What are two geological processes releasing carbon?

Answer 53

➊ CO₂ in the atmosphere reacts with moisture to form weak carbonic acid. When this falls as rain, it reacts with some of the surface minerals and slowly dissolves them i.e there is chemical weathering

➋ pockets of carbon dioxide exist in the Earth’s crust. Volcanic eruptions and earthquakes can release these gas pockets. This outgassing occurs mainly along mid-oceanic ridges, subduction zones and at magma hotspots.

Question 54

Where do biological processes sequester carbon?

Answer 54

On land and in the oceans.

Question 55

Compared with its geological counterpart, is biological sequestering faster?

Answer 55

Yes, biological sequestering operates on much shorter timescales, from hours to centuries.

Question 56

What will warm and wet conditions mean for carbon?

Answer 56

Will result in good plant growth, so more carbon absorbed.

Question 57

What will darker conditions mean for carbon?

Answer 57

Will result in less plant growth, so less carbon absorption.

Question 58

What are oceans ranked as in terms of carbon stores?

Answer 58

The oceans are the Earth’s second largest carbon store.

Question 59

Compared to the atmosphere, how much greater is the oceanic store of carbon?

Answer 59

The oceanic store of carbon is 50 times greater than that of the atmosphere.

Question 60

Where is most of the oceanic carbon stored?

Answer 60

Marine algae, plants and coral. The rest occurs in dissolved form.

Question 61

Define zooplankton.

Answer 61

Consists of the microscopic organism drifting or floating in the sea (or freshwater) along with diatoms, protozoa and small crustaceans

Question 62

What are the three types of oceanic carbon pump?

Answer 62

• biological pumps
• physical pumps
• carbonate pumps

Question 63

Describe the role of biological carbon pumps.

Answer 63

Move CO₂ from the ocean surface to marine plants (phytoplankton) by the process of photosynthesis (when green plants and other organisms use sunlight to synthesise (extract) nutrients from CO₂ and water.

At the surface of the ocean, there’s always an exchange of CO₂; some dissolves into the water as some is vented out into the air above.

Question 64

Describe the role of phytoplankton (micro-algae) in sequestering carbon.

Answer 64

• phytoplankton contain chlorophyll and need sunlight to live
• they take up (sequester) carbon dioxide through photosynthesis - creating calcium carbonate as their shells develop
• when they die, these carbon-rich microorganisms sink to the ocean floor and remain there, accumulating as sediment.

This particular process is known as the carbon pump and is part of the biological carbon pump.

Question 65

Why is the carbon pump (i.e the role of phytoplankton) so crucial?

Answer 65

Because it pumps CO₂ out of the atmosphere and into the ocean store. Without the contributions of phytoplankton, the CO₂ concentration in the atmosphere would be far higher then it already is.

Question 66

Despite the carbon pump (the role of phytoplankton) been an extremely efficient system, what else it it?

Answer 66

Extremely fragile, phytoplankton requires nutrients in vast quantities, and existing ocean temperatures and currents maintain a constant supply.

The recycling of particles that sink in deep waters by upwelling currents is critical. Slight changes in water temperature can alter the flow. Pollution and turbulence can also reduce light penetration and slow the pump down. Each of these factor is vulnerable to climate change - making the risk of the pump breaking down very severe.

Question 67

Describe the role of physical pumps in sequestering carbon.

Answer 67

Move carbon compounds to different parts of the ocean in downwelling and upwelling currents.

Question 68

Where does downwelling occur?

Answer 68

In parts of the ocean where cold, denser water sinks.

Question 69

What do downwelling and upwelling currents do with carbon?

Answer 69

Bring dissolved carbon dioxide down to the deep ocean.

Once there, it moves in slow-moving deep ocean current, staying there for hundreds of years.

Eventually, these deep ocean currents, part of the thermohaline circulation, return to the surface by upwelling. The cold deep ocean water warms as it rises towards the ocean surface and some of the dissolved CO₂ is released back into the atmosphere.

Question 70

What is the thermohaline circulation?

Answer 70

The global system of surface and deep ocean currents driven by temperature and salinity differences between different parts of the ocean.

It can be seen as a giant conveyor belt that moves water of varying temperatures and salinities through the oceans, playing a vital part in the carbon cycle.

Question 71

How does the thermohaline circulation work?

Answer 71

• the water in the far North Atlantic is cold and very saline - which makes it denser and heavier - causing it to sink
• by sinking, it draws warmer water in from the ocean surface above. This, in turn, draws water across the ocean surface from the Tropics/equatorial region.
• eventually, this movement from the Tropics draws cold water up from the ocean bottom, ready to be warmed again.

Question 72

Describe the role of carbonate pumps.

Answer 72

Form sediments from dead organisms that fall to the ocean floor. Particularly significant are the hard outer shells and skeletons of fish, crustaceans and corals. All are rich in calcium carbonate.

Question 73

What’s the bio-geochemical carbon cycle?

Answer 73

The continuous transfer of carbon from one store to another, through the processes of photosynthesis, respiration, decomposition and combustion.

Question 74

Describe the bio-geochemical cycle.

Answer 74

CO₂ is exchanged between the atmosphere and the oceans ➡ plants remove CO₂ from the atmosphere through photosynthesis ➡ animals consume plants and release CO₂ into the atmosphere and the water through respiration ➡ the decomposition of dead plants and animals releases CO₂ into soils and deposits carbon on the sea floor ➡ combustion - burning fossil fuels releases CO₂ into the atmosphere ➡ CO₂ is exchanged between the atmosphere and oceans

Question 75

Describe the triangle starting with tertiary consumers at the top.

Answer 75

• Top carnivores/tertiary consumers/apex predators e.g eagle
• carnivores/secondary consumers/omnivores e.g snake
• herbivores/primary consumers e.g squirrel
• photosynthesis/primary producers e.g plant
• soils/decomposers e.g mushrooms

Question 76

What does terrestrial mean?

Answer 76

Land-based

Question 77

𝗖𝗔𝗦𝗘 𝗦𝗧𝗨𝗗𝗬: What is happening to the Gulf Stream?

Answer 77

Scientists have suggested that global warming could lead to a slowdown - or even shutdown - of the vast system of ocean currents, including the Gulf Stream, that keeps Europe warm.

Question 78

𝗖𝗔𝗦𝗘 𝗦𝗧𝗨𝗗𝗬: What is happening to the Gulf Stream as global warming takes place?

Answer 78

As the world warms, melting icecaps and increased rainfall are widely predicted to slow the thermohaline circulation down.

Question 79

𝗖𝗔𝗦𝗘 𝗦𝗧𝗨𝗗𝗬: What happened during 2004?

Answer 79

The Gulf Stream appeared to stall for 10 days.

Question 80

𝗖𝗔𝗦𝗘 𝗦𝗧𝗨𝗗𝗬: What did data show regarding the speed of ocean circulation between the Gulf of Mexico and Europe?

Answer 80

Data seemed to show that the speed of ocean circulation between the Gulf of Mexico and Europe had slowed by 30% since 2000.

Question 81

𝗖𝗔𝗦𝗘 𝗦𝗧𝗨𝗗𝗬: What was the scientists’ hypothesis for the cause?

Answer 81

• melting Arctic ice was increasing the amount of freshwater entering the North Atlantic
• the ocean’s salinity was declining as a result, preventing cold water from sinking there
• this meant there was nowhere for the warm waters of the Gulf Stream to go - the North Atlantic was losing its pulling effect

Question 82

What are plants in the ecosystem?

Answer 82

Primary producers in the ecosystem.

Question 83

What do plants do to carbon?

Answer 83

Sequester carbon out of the atmosphere through the process of photosynthesis. In this way, carbon enters the food chains and nutrient cycles of terrestrial ecosystems.

Question 84

What happens to animals (consumer organisms) when they eat plants?

Answer 84

Respiration returns some of the carbon back to the atmosphere.

Question 85

What are biological decomposers?

Answer 85

Organisms such as insects, worms and bacteria that feed on dead plants, animals and waste.

Question 86

What’s the largest natural terrestrial carbon store?

Answer 86

Peatlands.

Question 87

Carbon fluxes within ecosystems vary on two timescales. What are they?

Answer 87

• 𝗱𝗶𝘂𝗿𝗻𝗮𝗹𝗹𝘆: during the day, fluxes are positive - from the atmosphere into the ecosystem. The reverse applies at night when respiration occurs but not photosynthesis.
• 𝘀𝗲𝗮𝘀𝗼𝗻𝗮𝗹𝗹𝘆: during winter, carbon dioxide concentrations increase because of the low levels of plant growth. However, as soon as spring arrives and plants grow, these concentrations begin to decrease until the onset of autumn.

Question 88

What’s carbon fixation?

Answer 88

Turns gaseous carbon - CO₂ - into living organic compounds that grow.

Question 89

Describe the role of trees in sequestering carbon.

Answer 89

• 95% of a tree’s biomass (leaves, branches, trunk, roots) is made up from CO₂ that it sequesters through photosynthesis and converts into cellulose (a carbon compound)

• carbon fixation turns gaseous carbon (CO₂) into living organic compounds that grow.

• leaf litter full of carbon goes into the ground bringing the carbon down with it.

Question 90

What does the amount of carbon stored in a tree/forest depend on?

Answer 90

The balance between photosynthesis and respiration.

Question 91

What are the predictions for the future regarding trees in sequestering carbon?

Answer 91

Deforestation, but net zero deforestation, so could see a reverse in trend.

Question 92

What can biological carbon be stored in?

Answer 92

Soils in the form of dead organic matter. This matter can be stored for decades or even centuries before being broken down by soil microbes (biological decomposition) and then either taken up by plants or released back into the atmosphere.

Depending on the nature of the soil this process can be relatively quick (a few years) or, as in tundra soils, very slow.

Question 93

Describe the role of mangroves in sequestering carbon.

Answer 93

• they are vital processors, sequestering almost 1.5 metric tonnes of carbon per hectare every year.

• mangrove soils consist of thick organic layers of litter, hummus and peat, which contain high levels of carbon - over 10%.

• undisturbed mangroves grow very quickly and absorb large amounts of carbon.

• submerged below high tides twice a day, their soils are anaerobic - without oxygen. Bacteria and microbes cannot survive without oxygen so the decomposition of plant matter is very slow. As a result, little of the carbon can be respired back into the atmosphere, and the store remains intact.

• i.e dead leaves, branches and roots containing carbon are buried in the soil, which is frequently, if not always, covered with tidal waters, This oxygen-poor environment causes very slow break down of the plant materials, resulting in a significant carbon storage.

Question 94

What are the problems mangroves face in sequestering carbon?

Answer 94

If mangroves are drained and cleared, carbon is released back into the atmosphere. Throughout the tropical world, mangroves are being cleared for tourism, shrimp farms and aquaculture.

Question 95

According to Malaysian researchers, what happens if just 2% of the world’s mangroves are lost?

Answer 95

According to Malaysian researchers, if just 2% of the world’s mangroves are lost, the amount of carbon released will be 50 times the natural sequestration rate.

Question 96

Where are mangrove forests found?

Answer 96

Along tropical and sub-tropical tidal coasts in Africa, Australia, Asia and the Americas.

Question 97

What are the predictions for the future regarding mangroves in sequestering carbon?

Answer 97

Decreasing coverage, predominantly due to tourism, beach access etc.

Taking away mangroves makes coasts more susceptible to flooding too as well as releasing carbon.

Question 98

Describe the role of tundra soils in sequestering carbon.

Answer 98

• much of the soil in the tundra region is permanently frozen and contains ancient carbon.

• microbe activity is only active in the surface layer of the soil when it thaws. The rest of the time, the roots and dead and decayed organic matter are frozen, locking any carbon into an icy store.

• tundra soils contain carbon that has been trapped for hundreds of thousands of years.

Question 99

What is permafrost?

Answer 99

A permanently frozen layer on or under Earth’s surface, it’s a huge terrestrial carbon sink, trapping plant and animal material in its frozen layers for centuries.

Question 100

What are the predictions for the future regarding tundra soils in sequestering carbon?

Answer 100

Climate change is melting permafrost, releasing carbon.

Question 101

Describe the role of rainforests in sequestering carbon.

Answer 101

• tropical rainforests are huge carbon sinks.

• carbon within rainforests is mainly stored in trees, plant litter, and dead wood.

• as the litter and dead wood decay, they’re recycled so quickly that a soil store doesn’t develop. Carbon given off by decomposers is rapidly recycled.

If they all died off, the world would lose a massive carbon sink.

Question 102

Give a statistic about tropical rainforests.

Answer 102

Tropical rainforests absorb more atmospheric CO₂ than any other terrestrial biome, accounting for 30% of global net production, although they cover just 17% of the Earth’s surface.

Question 103

What happens to carbon in animals?

Answer 103

In animals, carbon is synthesised into complex compounds e.g fats, proteins, and nucleic acids.

Question 104

What percentage of global carbon do soils store?

Answer 104

Soils store between 20% and 30% of global carbon.

They sequester about twice the quantity of carbon as the atmosphere and three times that of terrestrial vegetation.

Question 105

What does the amount of carbon stored in soil depend on?

Answer 105

• 𝗰𝗹𝗶𝗺𝗮𝘁𝗲 - dictates the rates of plant growth and decomposition; both increase with temperature and rainfall
• 𝘃𝗲𝗴𝗲𝘁𝗮𝘁𝗶𝗼𝗻 𝗰𝗼𝘃𝗲𝗿 - affects the supply of dead organic matter, being heaviest in tropical rainforests and least in tundra
• 𝘀𝗼𝗶𝗹 𝘁𝘆𝗽𝗲 - clay protects carbon from decomposition, so clay-rich soils have a higher carbon content
• 𝗹𝗮𝗻𝗱 𝘂𝘀𝗲 - cultivation and other forms of soil disturbance increase the rate of carbon loss

Remember that soils both sequester and release carbon dioxide.

Question 106

Why is a fully functioning and balanced carbon cycle important?

Answer 106

Vital to the health of the Earth in sustaining its other systems. Plays a key role in regulating the Earth’s temperature by controlling the amount of carbon dioxide in the atmosphere. Ecosystems, terrestrial and oceanic, also depend on the carbon cycle. The all important link between the atmosphere, hydrosphere, lithosphere, and biosphere.

Question 107

What is happening to the balanced carbon cycle?

Answer 107

It’s being increasingly altered by human activities.

Question 108

List examples of greenhouse gases.

Answer 108

• carbon dioxide
• methane
• water vapour
• nitrous oxide

Question 109

What are greenhouse gases?

Answer 109

Gases that both absorb and emit solar radiation and, in so doing, create the greenhouse effect that determines global temperatures.

Question 110

Define feedback

Answer 110

The impacts of change on the carbon cycle as carbon stores are released.

Question 111

What’s the (natural) greenhouse effect?

Answer 111

The warming of the atmosphere as gases such as CO₂ and CH₄ and water vapour absorb heat energy radiated from the Earth. Determines the distribution of temperature and precipitation.

Question 112

Describe the natural greenhouse effect.

Answer 112

➊ short wave radiation from the sun passes through the atmosphere
➋ some short wave radiation is absorbed by dark surfaces on Earth and converted into long wave (heat) radiation
➌ some long wave radiation passes back into space
➍ however, that warmth alone is insufficient to permit life on Earth, because it would simply to radiated into the atmosphere and lost into space unless something prevented it from escaping
➎ CO₂ and CH₄, along with nitrous oxide, halocarbons, ozone and water vapour absorb and reflect back some of the radiated heat from the Earth’s surface
➏ by retaining this heat, they keep the Earth’s surface 16°C warmer than it would otherwise be - warm enough to sustain life on Earth

It is this trapped, re-radiated, long-wave energy that constitutes the natural greenhouse effect and controls the mean global temperature. It also determines the distributions of both temperature and precipitation.

Without the natural

Question 113

Which greenhouse gas has the highest radiative forcing effect (RFE)?

Answer 113

CO₂ - it holds on to more heat for longer.

Question 114

What is the enhanced greenhouse effect?

Answer 114

The increase in the natural greenhouse effect, said to be caused by human activities that increase the quantity of GHGs in the Earth’s atmosphere.

Question 115

Describe the enhanced greenhouse effect.

Answer 115

➊ the concentrations of greenhouse gases in the atmosphere such as CO₂ have increased by 25% since 1750, when industrialisation began in the UK.
➋ Since the 1980s, 75% of CO₂ emissions have come from burning fossil fuels
➌ the disruption to Earth’s climate equilibrium caused by the increased concentrations of greenhouse gases has led to an increase in the global average surface temperatures
➍ more solar radiation is trapped under the thick blanket of GHGs as the concentration of GHGs in the atmosphere is higher
➎ less heat escapes back into the atmosphere and the Earth is dangerously warms up.

Question 116

Why is photosynthesis important in regulating the carbon cycle?

Answer 116

Photosynthesis by terrestrial and oceanic organisms plays an essential role in keeping carbon dioxide levels relatively constant and thereby helping to regulate the Earth’s mean temperature.

Question 117

Phytoplankton in the oceans sequester CO₂ through the process of photosynthesis - pumping it out of the atmosphere and into the ocean store. What is this action known as?

Answer 117

The biological carbon pump and the processes transfer 5-15 Gt of carbon from the atmosphere to the ocean each year.

Question 118

How many Gt of carbon does terrestrial photosynthesis (land-based) enable plants to sequester?

Answer 118

Terrestrial plants allows plants to sequester 100-120 Gt of CO₂ each year. This is then released back into the atmosphere through respiration and decomposition.

Question 119

What does increased photosynthesis of phytoplankton result in?

Answer 119

Algal blooms in Arctic waters. More CO₂ is absorbed there.

Question 120

The amount of photosynthesis varies spatially, particularly with…

Answer 120

net primary productivity (NPP). NPP is the amount of organic matter that is available for humans and other animals to harvest or consume. NPP is highest in the warm and wet parts of the world, particularly in the tropical rainforests and in shallow ocean waters. It is least in the tundra and boreal forests.

Question 121

Why is carbon important in soils?

Answer 121

Helps to give soils its moisture-retention capacity, its structure and its fertility.

• supports micro-organisms that maintain the nutrient cycle
• break down organic matter
• provide pore spaces in infiltration and storage of water
• enhances plant growth
• without carbon, the nutrient and water cycles cannot operate properly - the broken down organic matter provides spaces for infiltration and storage of water and the nutrients for plant growth.

Question 122

What does soil health depend on?

Answer 122

The amount of organic carbon stored in the soil. Organic carbon is located in the surface layer of the soil.

Question 123

What does healthy soil have?

Answer 123

A large surface area reservoir of available nutrients which, in their turn, condition the productivity of ecosystems.

• dark, crumbly, porous
• contain many worms and other organisms
• provide air, water and nutrients for micro-organisms and plants to thrive
• contain more carbon or organic matter
• sequester carbon
• improve resilience to wetter weather because they enable infiltration and percolation of water (reducing soil erosion and flood risk)
• retain moisture, which regulates soil temperatures during heatwaves and reduces the effects of droughts.

Question 124

What are fossil fuels?

Answer 124

A natural fuel such as coal or gas, formed in the geological past from the remains of living organisms.

Question 125

Why are fossil fuels important as long-term carbon stores?

Answer 125

They comprise of carbon locked away within the remains of organic matter. However, when they are burnt to generate energy, the stored carbon is released - primarily as CO₂ - into the atmosphere.

Question 126

What are the implications for the extra emissions of CO₂?

Answer 126

It is estimated that about half the extra emissions of carbon dioxide since 1750 have remained in the atmosphere. The rest have been fluxed from the atmosphere into the stores provided by the oceans, ecosystems and soils. The rate of carbon fluxing has sped up. Increased carbon dioxide in the atmosphere has led to:

• a rise in the mean global temperature
• more precipitation and evaporation
• sudden shifts in weather patterns
• more extreme weather events, such as floods, storm surges and droughts
• the nature of climate change is varying from region to region - some areas are becoming warmer and drier and others wetter

Question 127

List some possible implications of climate change on the climate.

Answer 127

• Atlantic and Southern Ocean thermohaline circulation may weaken, altering the transfer of heat by oceans

• Antarctic ice shelves will melt, adding more freshwater to the Southern Ocean, changing density and convection

• temperate and tropical zones may experience stronger storm activity as a result of more heat energy and moisture in the atmosphere, including more intense tropical cyclones and stronger mid-latitude westerly winds

• precipitation will increase in higher latitudes and decrease in lower latitudes

Question 128

List some possible implications of climate change on ecosystems.

Answer 128

• habitat changes will mean 10% of land species with limited adaptability will face extinction as the climate gets warmer and either wetter or drier. Rates of extinction could rise to 15 and 40% of all species (Arctic and Antarctic fauna will be affected such as polar bears)

• biodiversity will be affected as habitats shift poleward or into deeper ocean waters or higher altitudes. In north Brazil and central-southern Africa, lower rainfall and soil moisture, which caused changes to soil and oxygen, will reduce biodiversity

• tundra biome will be affected by thawing permafrost

• marine diversity may be lost as fish move away from warming sea temperatures and about 80% of coral reefs could be bleached (e.g Great Barrier Reef) Acidification of sea water will threaten corals and the shells of marine creatures will get smaller and thinner

• sea level: this is rising because of melting ice sheets and glaciers; many major coastal cities around the world are under threat from flooding by the sea

Question 129

List some possible implications of climate change on the hydrological cycle.

Answer 129

• rivers will dry up in regions where precipitation is reduced or less effective because of higher evaporation rates

• small glaciers will disappear (e.g in the Andes and Himalayas), decreasing river discharges once they have gone

• extreme heavy precipitation events will become common, with precipitation increases over northern-hemisphere land areas

• permafrost areas will thaw and add more water to Arctic rivers

Question 130

Describe the positive feedback loop (Arctic amplification)

Answer 130

temperatures warm ➡ increase warming of ocean waters/tundra surface ➡ sea ice cover/permafrost melts and shrinks ➡ methane and carbon dioxide released (and ocean waves now absorb more solar radian than highly reflective sea ice) ➡ temperatures warm

Question 131

Synoptic link between weathering and erosion and sedimentary rock

Answer 131

Weathering and erosion processes, such as those found at the coast or in a glaciated area, provide sediments and other elements that are deposited on the seabed to form sedimentary rock, some of which are important for storing carbon in a geological sink.

Question 132

Examples of outgassing

Answer 132

Common in geothermal areas, such as the CO₂ rich hot springs in Yellowstone, Iceland, and New Zealand.

Question 133

What do primary producers do?

Answer 133

Absorb CO₂ from the atmosphere through the process of photosynthesis and then release the gas back into the atmosphere through respiration.

Question 134

What has human activity transferred?

Answer 134

Considerable amounts of carbon from fossils stores, where exchanges are very slow, into the fast category, significantly disturbing the climate cycle.

Question 135

What does the IPCC estimate regarding CO₂?

Answer 135

That between 1750 and 2011 the concentration of CO₂ in the atmosphere increased by 40%, with combustion of fossil fuels adding 375PgC to the atmosphere and deforestation adding 180PgC

Question 136

Why is carbon vital in soils?

Answer 136

Without carbon, the nutrient and water cycles cannot operate.
• The broken down organic matter provides spaces for infiltration and storage of water.
• The broken down organic matter provides the nutrients for plant growth.

Question 137

Name 3 carbon stores

Answer 137

Atmosphere, oceans, terrestrial (trees)

Question 138

Stores can also be referred to as…

Answer 138

pools, sinks and reservoirs

Question 139

Carbon moving from one store to another is called…

Answer 139

flux

Question 140

CO₂ released by volcanoes is called…

Answer 140

out-gassing

Question 141

When CO₂ combines with rain water to form a carbonic acid, what occurs?

Answer 141

Chemical weathering, acid rain

Question 142

Breaking down of organic material and releasing CO₂ into the soils is called…

Answer 142

Decomposition

Question 143

Biomass and fossil fuels releasing CO₂ into the atmosphere is called…

Answer 143

Combustion

Question 144

Removing of CO₂ from the atmosphere to promote plant growth is called…

Answer 144

photosynthesis

Question 145

Example of a sedimentary carbonate rock

Answer 145

Limestone/chalk

Question 146

Taking in carbon

Answer 146

Sequestering carbon

Question 147

Two carbonate pumps in the ocean

Answer 147

1. Biological carbon pump
2. Physical pump

Question 148

What is phytoplankton?

Answer 148

Microscopic plant-like organisms that sequester carbon - start of the ocean food chain.

Question 149

The global movement of ocean currents due to temperature and salinity is called…

Answer 149

Thermohaline circulation

Question 150

What will happen if the Gulf Stream shuts down?

Answer 150

Europe will be colder. Could counteract climate change.

Question 151

What four terrestrial carbon stores did we look at?

Answer 151

1. Mangroves
2. Trees
3. Tundra
4. Rainforests

Question 152

3 main greenhouse gases

Answer 152

1. Carbon dioxide
2. Methane
3. Nitrous oxide

Question 153

Sources of methane

Answer 153

Rice paddy fields, gas pipeline leakages, cattle farming

Question 154

Sources of CO₂…

Answer 154

Burning fossil fuels, deforestation

Question 155

Why are healthy soils so important?

Answer 155

• Provide air, water and nutrients for micro-organisms and plants to thrive
• Sequester carbon - huge carbon store
• Improve resilience to wetter weather, because they enable infiltration of water (reducing soil erosion and flood risk)
• Maintains water cycle

Question 156

Permafrost melting and sea ice coverage reducing is part of what?

Answer 156

Arctic amplification

Question 157

Why are temperatures warming faster in the Arctic than the rest of the world?

Answer 157

When bright and reflective ice melts, it gives way to a darker ocean; this amplifies the warming trend because the ocean surface absorbs more heat from the Sun than the surface of snow and ice. Losing sea ice reduces Earth’s albedo: the lower the albedo, the more a surface absorbs heat from sunlight rather than reflecting it back to space.

Question 158

Explain the Arctic Amplification phenomenon

Answer 158

Temperatures have increased about twice as fast in the Arctic as in the mid-latitudes.

Question 159

Fossil fuel consumption impact: Arctic Amplification

Answer 159

The Arctic region is warming twice as fast as the global average. The phenomenon is known as Arctic amplification. Melting permafrost releases CO₂ and CH₄ leading to increased global temperatures and further melting. Which can then in turn affect albedo and ocean circulation.

Question 160

Fossil fuel consumption impact: Hydrological cycle

Answer 160

• Changes to temperature will lead to changes in precipitation patterns.
• Snowfall is likely to reduce.
• River discharge patterns would change.
• Glacial melt may increase.

Question 161

Fossil fuel consumption impact: Climate

Answer 161

• Global temperatures are increasing due to increased CO₂ in the atmosphere. Eastern and Northern Europe is expected to see warmer winters and Southern Europe is expected to see warmer summer.
• Extreme weather events are predicted to become more frequent and intense.

Question 162

Fossil fuel consumption impact: Balance

Answer 162

• If sources and sinks are equal, the carbon cycle is said to be in equilibrium.
• Fossil fuel consumption and deforestation increases CO₂ inputs into the atmosphere - this alters the balance of carbon pathways/flows.

Question 163

Why is a healthy soil important?

Answer 163

• Provide air, water and nutrients for micro-organisms and plants to thrive
• Sequester carbon
• Improve resilience to wetter weather, because they enable infiltration of water (reducing soil erosion and flood risk)